A random sample of 10 brands of vanilla yogurt was selected and the calorie count per serving was recorded, resulting in the following data: 130,160,150,120,120,110,170,160,110,90.
(a) Calculate the sample mean and the sample standard deviation. 1
(b) If we want to calculate a confidence interval to estimate the true mean calorie count for the population, what must be true (or what must we assume) for the interval to be valid?
(c) Calculate a 90% confidence interval to estimate the true mean calorie count.
(d) Calculate a 99% confidence interval to estimate the true mean calorie count.